1. The Field of the Invention
The present invention relates to a handling means for elongate items such as lengths of drill rods, poles, solid pipes, thin wall pipe, and the like.
Throughout the specification, the term “drill rod” will be taken to include all forms of elongate members used in the drilling, installation and maintenance of bore holes and wells in the ground and will include rods, pipes, tubes and casings which are provided in lengths and are interconnected to be used in the borehole.
2. Relevant Technology
One particular application of the invention relates to an accessory which can be used with drill rigs which are to be used in drilling bore holes. Such drill rigs generally comprise an upstanding mast which has a drill head mounted to it where the drill head is capable of movement along the mast and the drill head is provided with means which can receive and engage the upper end of a drill string and can apply a rotational force to the drill string to cause it to rotate within the bore hole whereby such rotation results in the cutting action by the drill bit mounted to the lower end of the drill string. The drill string includes a number of drill rods that are connected end to end. Each drill rod generally is at the most equal to the height of the mast. Frequently, each drill rod can have a length up to approximately six meters. During a drilling operation, when the drill head has reached the lower end of the mast, the drill string is clamped and the drill head is disconnected from the drill string. A fresh length of drill rod is then raised into position in order that the upper end of the fresh length is engaged to the drill head and the lower end of the fresh length is engaged with the upper end of the drill string. Once the fresh length of drill rod has been installed, the drilling operation can recommence until the drill head again reaches the lower end of the mast. During drilling activities of deep bore holes which may extend for hundreds of meters, it is necessary to locate fresh lengths of drill rod into a drill string at very regular intervals.
Often the drill rig is mounted to the chassis of a motorized vehicle such as a truck or lorry. The drill rods may be mounted in a storage zone such that they lie horizontally in a stacked array beside the drilling mast on the same vehicle. Alternatively, the drill rods may be mounted on a vehicle parked alongside the drilling rig or stacked on the ground beside the drilling rig.
One common method for raising a drill rod to the mast comprises mounting holder along the drill rod, connecting that holder to a cable carried by a winch located at the upper end of the mast, and then lifting the drill rod into position. This requires manipulation by a member of the drill rig crew who is required to support and guide the lowermost end of the length of drill rod as the length of drill rod is being raised into position. Due to the nature of drilling sites, this action can be quite hazardous. In addition, during the raising of the drill rod, it has been known for the upper portion of the drill rod to strike some obstruction on the drill mast which causes the lower end to move in an unpredictable manner, possibly resulting in injury to the crew member. In addition, this process requires joint coordination between the crew member guiding the one end and the other crew member controlling the winch.
Similarly during the raising of a drill string, it becomes necessary to regularly remove drill rods from a drill string and locate those drill rods in the storage zone located beside the mast which may either be located on the same vehicle as the drilling rig, on some adjacent vehicle, or on the ground beside the drilling rig. This can also create hazards for the personnel required to handle and store the drill rods.
In the past, alternative arrangements have been proposed for the handling of drill rods. Examples of such are described in AU693382 and U.S. Pat. No. 6,298,927. Throughout this specification, the discussion of the background and prior art to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia or the world as was at the priority date of the application.